Olanzapine (Zyprexa) Treatment and Dosing for Schizophrenia and Bipolar Disorder
For patients with schizophrenia or bipolar disorder, olanzapine (Zyprexa) should be administered at an initial dose of 5-10 mg once daily for adults with schizophrenia and 10-15 mg once daily for bipolar disorder, with target doses of 10 mg/day for schizophrenia and 5-20 mg/day for bipolar disorder. 1
Dosing Guidelines for Schizophrenia
Adults
- Initial dose: 5-10 mg once daily without regard to meals 1
- Target dose: 10 mg/day (typically reached within several days) 1
- Dose adjustments: Should occur at intervals of not less than 1 week
- Dose increments/decrements: 5 mg per day when needed
- Maximum recommended dose: 20 mg/day (doses above 10 mg/day were not demonstrated to be more efficacious) 1
Special Populations
- Starting dose of 5 mg recommended for:
Adolescents
- Starting dose: 2.5 or 5 mg once daily
- Target dose: 10 mg/day
- Mean modal dose in clinical trials: 12.5 mg/day
- Maximum dose: 20 mg/day 1
Dosing Guidelines for Bipolar I Disorder (Manic or Mixed Episodes)
Adults
- Initial dose for monotherapy: 10 or 15 mg once daily 1
- Dose adjustments: At intervals of not less than 24 hours
- Dose increments/decrements: 5 mg per day when needed
- Effective dose range: 5-20 mg/day
- Maximum dose: 20 mg/day 1
Adjunctive Treatment
- Initial dose with lithium or valproate: 10 mg once daily 1
- Effective dose range: 5-20 mg/day
Adolescents
- Starting dose: 2.5 or 5 mg once daily
- Target dose: 10 mg/day
- Mean modal dose in clinical trials: 10.7 mg/day
- Maximum dose: 20 mg/day 1
Administration Options
- Oral tablets taken once daily without regard to meals
- Orally disintegrating tablets (ZYPREXA ZYDIS) available for patients with difficulty swallowing
- Intramuscular injection (5-10 mg) available for acute agitation 1
Efficacy and Clinical Considerations
Schizophrenia
- Olanzapine is effective against both positive and negative symptoms of schizophrenia 3
- Superior to haloperidol in overall improvements in psychopathology and treatment of negative symptoms 3
- Lower 1-year risk of relapse compared to haloperidol 3
Bipolar Disorder
- Effective for acute manic or mixed episodes 1
- Can be used as monotherapy or adjunctively with lithium or valproate 1
Monitoring and Safety
Common Adverse Effects
- Weight gain (most significant compared to other antipsychotics) 3
- Somnolence and sedation
- Dizziness
- Anticholinergic effects (constipation and dry mouth) 3
- Transient asymptomatic liver enzyme elevations 3
Metabolic Considerations
- Regular monitoring of weight, BMI, blood pressure, fasting glucose, and lipid panel is recommended
- Olanzapine has a higher risk of weight gain compared to some other atypical antipsychotics 3
Advantages Over Typical Antipsychotics
- Significantly fewer extrapyramidal symptoms than haloperidol 3
- Not associated with agranulocytosis (unlike clozapine) 3
- No clinically significant hyperprolactinemia (unlike risperidone) 3
- No QT interval prolongation 3
Special Situations
Treatment-Resistant Schizophrenia
- Some case reports suggest benefit from higher doses (35-60 mg/day) in treatment-resistant cases, though this exceeds approved dosing 4
- Limited controlled evidence supports doses above 20 mg/day, with increased risk of side effects 5
Acute Agitation
- Intramuscular olanzapine (10 mg) is effective for acute agitation in schizophrenia and bipolar disorder 1
- Lower doses (5-7.5 mg) may be considered based on clinical factors 1
Long-term Treatment
- Periodically reassess the need for maintenance treatment
- For maintenance in schizophrenia, 10-20 mg/day has been shown effective 1
- For maintenance in bipolar disorder, 5-20 mg/day has been shown effective 1
Remember that while higher doses may be used in clinical practice, the risk of adverse effects increases with dose, and evidence supporting efficacy of doses above 20 mg/day is limited. Always start with the lowest effective dose and titrate carefully based on response and tolerability.